"It recently has been suggested that using vegetable oils to fry food may be bad for your health due to the production of toxic chemicals called aldehydes during the heating process. Aldehydes are simple organic structures – compounds which contain a carbon-oxygen double bond – and are abundant in nature. They are formed in the human body in small amounts as by-products of normal fructose and alcohol metabolism. Consumption of dietary aldehydes is thought to contribute to human diseases including diabetes and heart disease. But what about olive oil? Is it classed as a vegetable oil, and is it safe to fry food with it?"